MIPS Program: Getting some errors

I am trying to write this program where,
I need to print a loop of 3's multiples and repeat that loop 15 times.

In other words I need to print this series 15 times:
3, 6, 12, 15, 18...

I am using Spim for my code. Upon runing I get some exceptions.I am totally new with this language and don't really know how to interpret this exceptions. Does this exceptions means the errors?
If so please can you look at my code and explain me how to correct my code?